The country collectively gasped when contestant Rachel Frederickson walked out during the February 4 finale of NBC’s The Biggest Loser — and not necessarily for good reasons. The 24-year-old eventual winner even left trainers Jillian Michaels and Bob Harper uncomfortably shocked with her 155-pound weight loss, bringing her down to a mere 105 pounds. At first Rachel avoided addressing her extreme makeover, but now she’s admitting she may have taken things too far.

Rachel broke show records when she dropped to a size 0-2, but many were fearful that her BMI (at 18, it’s well below the threshold doctors consider normal for a 5’4’’ person like her) was a warning sign. Not setting anyone at ease, the voice over artist from L.A. explained that she consumed 1,600 calories daily and would work out six hours each day during the three months period prior to the finale.

Now, just over one week later, Rachel is opening up to People about her extreme training, and whether she may have overdone it. "Maybe I was a little too enthusiastic in my training to get to the finale," she admits in the new issue of the mag. But for those who are crying eating disorder, she has a very clear message: "I am very, very healthy."

But an In Touch Weekly source has revealed that Rachel did turn to additional extreme measures for her weight loss. The insider says that she used an infrared sauna — which uses infrared radiation — to burn calories and boost metabolism.

“She came in almost every day for two-and-a-half weeks before the finale,” the source at Firm Body Evolution in LA says. “You can burn up to 600 calories in a half-hour session, although everyone is different,” the source explains

For their part, the producers of Biggest Loser say that they carefully monitored Rachel throughout both her run on the show and the weeks before the finale. Reveals producer Dave Broome, “Rachel passed all the required medical tests ensuring she was healthy.” Though her on-air fitness coach Dolvett Quince does say that he was taken aback by her appearance."The first thing that went through my mind was, 'That's just too much,' " he concedes.

What do you think of the way Rachel lost the weight? Tell us in the comments below.